He implored his fellow congressmen to support a bill that would shut down the three plants in the U.S. that kill horses and send them to Europe ``for some warped demand among foreign diners.''

The bill passed handily and now faces an uncertain future in the Senate. Some on the congressional floor groused about spending time on horse meat at the expense of other matters.

But, in the process, they missed an opportunity to take a good look at the odd moral calculus we use when deciding what to have for dinner.

For instance, why is it ``warped'' and ``repugnant'' to eat horses but not cows, pigs and chickens? How did horses get a pass? Or, for that matter, monkeys, dolphins and other creatures that never make it on the menu?

Supporters of the bill would argue that horses helped settle the country and have served as humans' companions.

``Horses and other equines play a vital role in the collective experience of the United States and deserve protection and compassion,'' reads the proposed ban.

Others place horses in that elite group of ``intelligent'' animals, the kind that performs tricks and presumably leads richer emotional lives than your average barnyard critter.

Oddly, the bill doesn't actually prohibit horse slaughter -- it just prevents slaughtering horses for human consumption. What is it about eating certain animals that sparks such emotions? As much as we try to make sense of what we find palatable, says food writer Bunny Crumpacker, our appetites defy logic.

``If we were rational, we would eat spiders -- juicy tarantulas! -- as well as lobsters,'' she writes in her book ``The Sex Life of Food.'' ``We'd eat mice and rats as well as frogs, snails and crabs.''

Few of us would think to enhance our food with insect secretions. Unless, of course, you're talking about honey. And while plenty of animals produce milk -- in certain parts of the world, it's common to drink milk from yak, buffalo and camels -- we've limited ourselves to the dairy of cows and goats.

Despite what we tell ourselves, Crumpacker says, we don't abstain from eating horses, dogs and cats because they suffer more than other animals. It's simply because we interact with those animals.

``We've turned puppies and dogs and horses into extensions of ourselves,'' she says from her home in New York. ``So when you think of eating a dog, it's almost like cannibalism.''

We've become distant from agricultural matters, physically and emotionally. That's why we call cow meat ``beef'' and pigs ``pork.'' Think of how tough restaurateurs would have it if their menus featured ``baby cow parmesan.''

One argument for protecting horses is that they're smarter than the average livestock animal, have a greater self-awareness and fear their own deaths at the slaughterhouse.

Determining the intelligence of any species is a tricky matter; emotions even trickier. One common gauge of intelligence is how well they respond to training. Dogs, horses and dolphins all excel in this regard, and all are well outside the American palate.

Joe Greenbacker's cows don't fetch, let alone make their way through obstacle courses. But they do exhibit what you might call personalities, a controversial term in the field of animal psychology.

On his Durham farm, Greenbacker walks through the barn that houses nearly 300 milk cows and points to some that are standoffish, others downright pushy. He pets one cow named Chocolate Chip and watches as she follows him behind the fence, seeking more affection.

Because of these individual traits, it's tough not to forge relationships with some of the cows. It's hard when the older ones have to go to auction and eventually be slaughtered, he says, but it's a part of farm life. Greenbacker says his daughter, who helps run the farm, has a tougher time with it.

Though the cows definitely have their own temperaments, Greenbacker can't say for sure if they have actual emotions. ``I think any time you try to assign human characteristics to animals, you're taking it on faith,'' he says. ``It's not really science-based.''

But researchers have increasingly taken a scientific approach to the matter of animals and emotions. Once considered a fringe pursuit, animal psychology has gained significant ground in recent years.

Lori Gruen, who teaches philosophy at Wesleyan University, says our thoughts about the intelligence of animals is based on human standards of intelligence. Chickens might not do tricks, but are ``highly intelligent and social.''

``In the flock, they have the ability to remember certain types of hierarchies,'' says Gruen, who writes frequently on the ethics of animal treatment.